ATI 6000 series

I heard that ATI will launch their 6000 series next month. Can someone tell me whether ATI planned to release economic/low power version of 6000 series (like 4670 in 4000 series or 5670 in 5000 series)?

And I would like to know what are the difference between 5000 and 6000 series? New memory/New version of DirectX/More cores?

Thanks for your answers.